1. Field of the Invention
The present invention relates generally to the area of x-ray imaging systems and devices used with such diagnostic x-ray systems. More specifically, the present invention relates to the field of a C-arm imaging apparatus incorporating a new and improved orbital braking mechanism for holding the C-arm in position relative to the yoke by use of a single piece yoke and for achieving wear compensation of the orbital brake without disassembly of the C-arm.
2. Background of the Invention
It is frequently desired to conduct an x-ray examination of a patient by positioning the x-ray equipment such that a number of different views of the area of interest, and from several different positions, may be obtained. It is also preferable to do so without the need to reposition the patient. Mobile C-arm x-ray diagnostic equipment, such as that shown in FIG. 1, has been developed to meet these needs and is now well known in the medical and surgical arts. The C-arm x-ray machine is especially useful in that it is small enough and mobile enough to be present in an operating or exam situation without requiring the physician to repeatedly move or requiring the patient to change positions to obtain a suitable image. This usage, however, also requires frequent movement and repositioning of the equipment itself.
C-arm imaging systems are widely used in the medical arts. Examples of their uses include bone density measurement and fluoroscopic imaging during surgical procedures. The term xe2x80x9cC-armxe2x80x9d refers to the generally C-shaped member that has an x-ray source and an image receptor, or detector, mounted on opposing ends of the C-arm. In this fashion, x-rays emitted by the source are incident on and detected by the detector. The x-ray source and the detector are positioned such that when, for example, a human extremity is interposed between the x-ray source and the image receptor, thereby exposing the extremity to x-ray radiation, the receptor produces data representative of characteristics of the interposed extremity. The data produced is then displayed on a monitor and electronically saved.
The C-arm portion of the machine is normally mounted such that it is permitted two degrees of freedom. First, the C-arm track is slidably mounted to the C-arm support, or yoke, so as to be movable in relation to the yoke. This permits the x-ray source and image receptor to be moved rotatably about the arc of curvature of the track in the C-arm. Second, the C-arm support member permits rotation of the C-arm about its axis. Mobile C-arm machines also have a third degree of freedom in that they are free to move horizontally along the floor and a fourth in that the C-arm can be raised and lowered.
C-arm x-ray equipment must be delicately positioned in order to render the image or images desired or required by the physician. Unfortunately, the weight of the supporting structure makes it difficult to position the C-arm. Therefore, it is desirable to design a source of frictional drag between the C-arm and the C-arm""s support member as well as on the C-arm track.
It is also desirable to balance the C-arm, the x-ray source, the x-ray detector and the Yoke so that relatively little physical effort is required to move the C-arm about the orbital rotation axis and the lateral rotation axis. One manner of accomplishing this is to design the C-arm such that its center of mass is as close as possible to the orbital and lateral rotation axes. Nearly balanced C-arms also require less braking force to be locked into place.
Prior devices are frequently equipped with a C-arm brake that can only be adjusted by opening the yoke. Some of these devices actually require a two-piece yoke. The device of the present invention eliminates the need for a two piece yoke and further eliminates the need for downtime while the yoke is being taken apart and the brake advanced.
Accordingly, it is an object of the present invention to provide such a C-arm brake that allows for wear compensation while allowing for the use of a single piece yoke, which improves manufacturing simplicity and reduces cost. It is another object of the present invention is to allow adjustment of the brake without disassembly. Yet another object of the present invention is to provide a device that can accommodate for manufacturing variances. It is still another object of the present invention to provide such a device that requires relatively few parts and can be easily manufactured. It is yet another object of the present invention to provide an aesthetically pleasing and aseptic device overall.
The device of the present invention has obtained these objects. It provides for a yoke interposed between the support arm and the C-arm of the C-arm x-ray machine that provides support for the C-arm and also allows for a single piece yoke. The device of the present invention also provides a plurality of discrete adjustments of the brake with no disassembly of the yoke being required. The present invention further provides for a device that accommodates for small variances in manufacturing. The device of the present invention is also relatively simple to construct and easy to operate, in addition to being aesthetically pleasing. Additional objects and advantages of the device of the present invention will be set forth in the description that follows. Other objects and advantages may be learned by practice of the invention.